Rebound preventing means for



Oct. 28, 1952 w. A. ANDERSON REBOUND PREVENTING MEANS FOR DIFFERENTIALACTUATORS Original Filed June 2'7, 1946 Patented Oct. 28, 1952 REBOUNDPREVENTING MEANS FOR DIFFERENTIAL ACTUATORS Walter A. Anderson,Bridgeport, Conn assignor to Underwood Corporation, New York, N. Y., acorporation of Delaware Original application June 27, 1946, Serial No.

679,722, now Patent No. 2,536,524, dated January 2, 1951. Divided andthis application December 7, 1948, Serial No. 63,965

3 Claims.

This invention relates to adding and computing machines in general, andmore particularly to means in such machines to provide bettercontrolled, smoother terminated movement of differentially movableelements.

The subject matter herein constitutes a division of Application No.679,722,'filed June 2'7, 1946, now Patent No. 2,536,524, issued January2, 1951.

Most adding and computing machines include elements which arecycle-operated to different extents in accordance with digit valuespredeterminedly indexed, or in accordance with digit values standing ina register and required to be transferred and/or total printed. Usuallythe imparted differential movements are terminated rather abruptly,causing the differential elements and related parts to jar and reboundexcessively,

particularly in machines which operate at high speed. The jarring andrebounding action places a strain on the mechanism, results inobjectional noises, and, most detrimentally, often results in erroneouscomputations. If the machine embodies means for printing computedvalues, the jarring is apt to cause the printing of erroneous digits andhas the eliect of causing blurred imprints.

It is an object of the invention to provide efficient means wherebydifferential movements of register driving or digit-representingelements are terminated efiiciently without detrimental jarring andrebounding.

It is another object of the invention to provide reliably operative,simple means, to counteract or suppress rebounding of differentiallymovable register-driving or digit-representing elements incidental totheir arrest at appropriate digitrepresenting positions, thereby toprovide for smoother and more reliable operation of the machine.

The invention has been worked out and is illustrated and described asembodied in the wellknown Class D Sundstrand Accounting Machine, themain and conventional features of which are disclosed in the patents toSundstrand, Nos. 2,194,270 and 2,209,240, dated respectively, March 19,1940 and July 23, 1940.

Referring to the drawings:

Figure 1 is a right-hand sectional side elevation, illustrating innormal position the printing I and computing devices of the machine, andin association therewith a provision to counteract rebounding ofdifierentially movable elements comprising type-bars and relatedelements at the instant of arrest. I

Figure 2 represents some of the parts seen in Figure l, and moreparticularly a differentially actuatable type-bar at the instant ofdifferential arrest during amachine cycle, and means in the act ofopposing the rebound tendency of the typebar.

Referring now to Figure 1, there are mounted to rise to diiierentialpositions in front of a platen l, a series of laterally adjacenttype-bars it! of various denominational orders. Said typebars 10 areeach provided with a vertical row of digit-types 8, and are supported ina stationary framework 1 of the machine, as at H and 15, fordifferential vertical sliding movement from retiring positions below atyping line at 13, to various raised positions wherein properdigit-types 8 are presented in front of said typing line 13. Thetype-bars have associated therewith an upper and a lower main register,respectively numbered 16 and ii, each capable of addition as well assubtraction. These registersifi and H henceforth will be referred to ascrossfooters. The type-bars 10 have also associated therewith an upperand a lower group of plain adding registers, all disposed to the rear ofthe crossfooters, the registers in these two groups being respectivelydesignated by the numerals I8 and I9. In order to cause the types on thebars I!) to record amounts, usual numeral keys, not shown, are providedto set up proper stopping conditions in a field of stop pins 2|, therebyto predetermine the differential extents to which the type-bars l0, anddownward extensions [0a for driving the crossfooter 11, are to riseunder the tension of springs 22. It will be noted that there is one suchspring for each type-bar l0, and one for each type-bar extension we, andthat each such spring is associated'with a lift arm 23 that isarticulated with a type-bar or its extension, as at 24. Normally thetype-bars ID are held in low, retired positions by two universal bars25, each one overlying a gang of said lift arms 23.

The cycling mechanism comprises two reciprocative crank arms 26 on ateach side of the group of type-bars 10, both crank arms being fixed upona main rock shaft 21 of the machine, and carrying rollers 3| that engagewith forked ends 32 of two levers 33, said levers 33 carrying the upperrestoring bar and being pivoted upon a stationary rod 34, upon whichalso the type-ba lifting arms 23 are pivoted. Laterally spaced verticallinks 35 connect the opposite cycle-controlled levers 33 with twolaterally spaced arms 36 which support the restoring bar 25 for thelower lifting arms 23. Said spaced arms 36 and the lifting arms 23 forthe type-bar extensions [to are mounted on a common pivot rod 38. Saidlinks are pivoted to the arms 33 and 35 upon laterally extending ends ofthe universal bars 25, and are held thereto by heads 39 of screws. Whensubsequent to indexing an amount in the keyboard a machine cycle isinstituted by the depression of a cycle key, not shown, the two crankarms 26 move anti-clockwise, and their rollers 3i move rearwardly andupwardly and cause said levers 33 and 36 with their rods 25 to rise,thereby permitting the type-bars H) to ise appropriate extents under thepower of the springs 22, in accordance with the setting of the stop pins2 l, as shown in Figure 2. To the above end, each type-bar 10 has aforwardly reaching arm 49 hingedly attached thereto at a verticallydisposed axis, as at 4|. At their forward ends the arms 40 reach intoslots provided in rods 42, the latter of which are guided for verticalmovement in a denomination shifting slide 43, the same as disclosed insaid patents to Sundstrand.

The type-bars l6 rise differentially to their appropriate digitpositions during the first half of the reciprocative cycle movement ofthe crank arms 26, and are forcibly restored against the tension of thesprings 22 by the return reciprocation of the crank arms 26, at the endof which the roller 3! has ridden onto a dwell 49. Thus all type-bars Kare normally locked against spring-urged upward movement.

At the very beginning of the return movement of the crank arms 26, analigner blade 46, cyclecontrolled in a usual manner, moves into whateverone of a series of detent notches 41 on the type-bars has become locatedopposite thereto. The operating mechanism for the aligner blade is notshown, but it firmly locates and locks the raised type-bars foroperation of those types 8 which. have become located opposite thetyping line 13. The selected types 8 are actuated against the platen byhammers 48, just subsequent to the operation of the aligner blade 48,the blade, as well as the hammers being restored just before the returnmovement of the type-bars commences. Each of the rollers 31 engages adwell 51 on the associated lever 33 at the end of the forward half ofthe cycle, and thereby provides for a delay in the return of thetype-bars, during which the type hammers 48 have time to operate andwithdraw.

Each of the crossfooters i and I! comprises a series of pinions 5'2rotatably mounted upon a transverse shaft 53. These shafts 53 aremounted for movement fore and aft of the machine, and each of the twosets of pinions 52 is located between two sets of racks 54 and 55, theracks 54 being adding racks and the racks 55 being subtracting racks.The adding racks 54 and the subtracting racks 55 are respectivelyattached to rearward branches 5"! of the type-bars l0 and theirextensions Eta, by means of mounting studs 58 which reach from saidbranches through vertically elongated openings 60 in said racks. At thelevel of the crossfooters, the racks 54, 55 are guided in transverselyslotted horizontal bars 52. Contractile springs 6! associated with saidracks 54, 55, and anchored to downward reaches of said branches 5?,tension the racks downwardly for the purpose of tens transfer.Conventional automatic and manual controls, not shown, are provided forcausing engagement of the individual crossfooters with either of theirassociated sets of racks'54, 55 at the beginning of the second halfcycle of the mach ne, to cause the type-bars,

during their descent, to drive either or both said crossfooters, eitheradditively or subtractively. Tens transfer blocking elements 64 arecapable to arrest the racks 54, 55 after a descent corresponding to theindexed number, but when'a register wheel 52 is to receive a transferfrom the wheel of the next lower order, a carry tooth 63 on such lowerorder wheel will trip a transfer control to free it from an edge of theassociated rack guiding bar 62, and thereby to cause the blockingelement 64 in control of the rack 54 or 55 which is to receive thetransfer, to move out of blocking position under the urge of a spring66. In each instance where this occurs, the active rack 54 or 55descends an extra step. In all instances where there is to be nocarrying operation, the blocking elements 64 will remain in place andthe springs 61 will be stretched after the racks 54 or 55 have becomearrested.

True positive and negative totals can be taken from either of thecrossfooters in the conventional manner, and when this is done, thecrossfooter from which the total is taken is in engagement with eitherthe adding racks 54 or the subtracting racks 55 depending on thepositive or negative nature of the total, the engagement being confinedto the up-strokes of the type-bars l0. Prior to a total printing cycle,the transfer controls 65 are all in their restored positions, and duringthe total printing cycle, when the typebars 10 rise, the transferinstituting teeth 63 on the crossfooter wheels 52, in cooperation withthe transfer controls 65 limit differentially the rise of the engagedracks 54 or 55, and therefore the type-bars It]. This is in accordancewith the digit values contained in the individual register wheels at theoutset of the total printing operation.

Inasmuch as this stopping action is sudden, the type-bars l0 andconnected parts obviously have a tendency to rebound, the same as whendifferential movements are terminated under control of the index pins2|.

A common set of racks 68 serves to drive all adding registers l8, andanother common set of racks H serves to drive all adding registers IS.The racks 68 and H are mounted for vertical movement in guides I2. .Attheir lower ends, the various racks 68 and H are connected to arms 13that are pivotally mounted on the rods 34, 38 on which the aforesaidlifter arms 23 for the type-bars IO and extensions lOa are respectivelymounted. Each of the arms 13 has a loose connection 14 with an arm 15which is integral with the type-bar lifter arm 23 of the appropriateorder and forms therewith a lever, said loose connections l4 affordingrelative movement between the related arms 13 and. I5. Whenthetypebars[0 rise in accordance with the indexed digits, the racks 68, H willdescend correspondingly. Conversely, as the type-bars descend during thesecond half of the machine cycle, the racks 68, H will rise.Conventional control mechanism is provided to condition the registers l8and I9 selectively for additive engagement with their associated sets ofracks 68, II at the beginning of the return stroke of the cycle, and tomaintain the engagement for the remainder of the cycle. Springs 18connected to the arms 13 and I5 provide a yielding connection betweenthese arms, so that differential movement of the typebarslfl may beconveyed to the racks 68, H, and provision made for tens transfermovement of the racks as in the case of racks 54, 55. The arrest of theindividual racks 58, H occurs under control of the usual carry-overcontrols indicated at I6, 71, such controls stopping the upward movementof the racks except where carrying operations are necessary. As in thecase of the spring 6| for the racks 54, 55, the springs 18 are stressedduring the last unit of downward movement of the type-bars in allinstances where no carrying operation is to take place.

In a manner fully disclosed in the aforesaid patents, a total may betaken from any one of the rear registers l8 and I9, and when this isdone, the type-bars [0 are arrested in a manner similar to thatexplained in connection with the cross-footers l6 and I1, and thereexists the same tendency for the type-bars to rebound in this instance.

The aforesaid tendency of the printing bars [0, together with relatedparts, to rebound, either in item entry or total printing operations, isreliably overcome by the provision of a series of resiliently activecam-arms (H9, one being provided for each type-bar l0 and beingassociated with a roller 62! on the type-bar lifter lever 23. Thesecam-arms 6!!! are instrumental to exert an impositive,rebound-counteracting force on their associated type-bars when eachtype-bar durin an item entry arrives in its appropriate raised positionas determined by a stop pin 2|. The same is obviously also the case whenin a total taking operation the type-bars I0 are differentially arrestedby the controlling register wheels, as stated hereinbefore. Saidcam-arms 6 l 9 are carried upon a common rod 62| which extendsintermediate the two spaced lever arms 599 that are integral with thebail-rod-supportingarms 36. Spacing collars on the rod, not shown,appropriately locate the individual cam-arms in operative alignment withtheir related rollers 62 El. Said cam-arms 619 are pivotally loose onsaid rod 62! and are under the constant clockwise urge of springs 622having anchorage on a common rod 623 extending between the arms 599.Short tails 524 of the cam-arms BIS bear normally against the undersideof the rollers 628 under the tension of the springs 622 but have nomoving tendency upon the rollers. In the normal state of the machine, asshown in Figure 1, short cam-shoulders 625 lie behind the rollers 620. Adwell surface 626 lies between the shoulder 625 and the pivot 62 l.

During each machine cycle as the type-bars are allowed to rise by thelifting of the bail rods 25, and so long as the type-bars do not becomearrested, the shoulders 625 of the cam-arms 619 follow behind therollers 52!] in their normal position. However, as viewed in Figure 2,just as soon as each type-bar is arrested under control of one of thestop pins 2!, the cam-shoulder 62 5, due to continued upward motion ofthe lower bail-rod 25, contacts the roller 520 and moves downwardlytherealong to suppress type-bar rebounding, the rebound suppressingaction of each shoulder G25 continuing as long as the shoulder 625remains in contact with the roller 620. The cam-shoulders 625 have anangle of attack with the rollers 525 suiiicient to afford adequateresistance against the rebounding action of the type-bars, but notsufficient to interfere with the operation of the cycling mechanism.After each type-bar is arrested, and rebounding has been overcome, theroller 62D rides along the dwell 625 to whatever degree is prescribed bythe rise of the type-bar. It will be noted from Figure 1 that the camfaces 625 normally lie a short distance from 6 the rollers 62%). This isto eliminate tl e need for accuracy of manufacture but the space isunder no circumstances large enough to permit entrance of the alignerblade 46 into a Wrong notch 41.

In Figure 2 the type-bar it has moved upwardly to the limit establishedby the rearwardly projected index pin 2|. A little further in the cycle,the aligning bar 45 will move into the notch 41 which has been presentedopposite it. It will be appreciated that in the absence of the describedrebound preventing structure the chance for entry of the aligning bar 46into a wrong notch 41, would be particularly prevalent in the case suchbar is arrested in its highest digit position, it being understood thatin such event the aligning bar 46 moves to efiective position only aninstant later.

With the described rebound preventing structure, the type-bars l0 andconnected parts come to rest promptly and eiliciently, eliminating anychance of mis-operation of the machine.

Variations may be resorted to within the scope of the invention.

What is claimed is:

1. In a machine of the class described having a means movabledifferentially from a normal position to different digit-representingpositions, means for urging said movable means to the latter namedpositions, stop means for said movable means conditionable to stop thelatter upon movement to a desired digit-representing position, controlmeans normally engaging said movable means to hold it in normalposition, means for operating said control means to enable said urgingmeans to drive said movable means until arrested by the said stop means,said control means moving away from the movable means after the latteris arrested by said stop means, and means including a cam elementoperating between said control means and the movable means, andeffective to apply to the latter, during the initial portion of theseparation of said control means and said movable means areboundcounteracting force, said cam element having a dwell rendering itnon-impeding to the control means during the remainder of the movementof the control means away from said movable means.

2. In a. machine of the class described having a series ofdifferentially movable elements, indexable means to establish digitrepresenting limits of movement for said elements, actuating means forsaid elements, power means contacting said elements to controldisplacement thereof by said actuating means, projections on saidelements and a spring tensioned cam element carried by said power meansfor each element, said cam element engaging said projection and exertinga rebound suppression force thereon only during a short movement of saidpower means following the arrest of said element by said indexablemeans.

3. In a machine of the class described having a plurality ofdiiferential elements, each movable from a normal to a digitrepresenting position, means urging each said element from normalposition, a universal power operated bar restraining movement of saidelements, indexable means settable to arrest said elements at digitalrepresenting positions, means to reciprocate said universal bar toenable advance of said elements and to restore them to normal position,said universal bar moving away from said elements as they are 2,615,6227 8: arrested, a projection on each differential ele- REFERENCES CITEDment; a plurality of rebound preventing cam arms The followingreferences are of: record in lthe one for each element, movable-withsaid universal of this patent: bar, and spring means to urge said camarms into engagement with said projections, said cam arms 5 UNITEDSTATES PATENTS being so formed as to apply a rebound prevent- NumberName Date ing force to each differential element as said ele- 2,111,122Mills et a1 Mar. 15, 1938 ment engages said indexable means and leaves2,194,270 Sundstrand Mar. 19, 1940 said restraining bar; 2,297,803Scheerer et a1 -Obt. 6-,1942 WALTER A. ANDERSON. 10 2,490,200 BoydenDec. 6; 1949

